1. Field of the Invention
This invention generally relates to a bicycle rear derailleur. More specifically, the present invention relates to a bicycle rear derailleur that reduces noise that may occur while riding on rough roads, trails or the like.
2. Background Information
A bicycle rear derailleur is used to selectively move a chain from one of a plurality of sprockets to another for changing speeds of the bicycle. A typical rear derailleur has a base member, a movable member supporting a chain guide and a linkage assembly (e.g., a moving mechanism) coupled between the base member and the movable member so that the chain guide moves laterally relative to the base member. The base member is typically coupled to the rear end of the bicycle frame by a bolt that forms a B-axle for providing limited rotation with respect to the bicycle frame. The chain guide typically includes a pair of guide plates that rotatably support a guide pulley and a tension pulley between the guide plates. The chain guide is typically coupled to the movable member by a shaft that forms a P-axle for providing limited rotation of the chain guide with respect to the movable member. The linkage assembly typically includes a pair of pivotal links pivotally coupled to both the base member and the movable member. A spring typically biases the chain guide to an innermost or outermost position relative to the rear sprockets. A Bowden-type control cable with an outer sheath and an inner wire is typically coupled between the rear derailleur and a conventional shift control device. Thus, the chain guide can be moved laterally by moving the linkage assembly via the inner wire. In particular, one end of the control cable is typically connected to one of the links, and another end of the control cable is connected to a shift control device mounted on the bicycle handlebar. When the rider operates the shift control device, the operating cable is pulled or released accordingly. Pulling the inner wire moves the chain guide against the biasing force of the spring, while releasing the inner wire causes the chain guide to move due to the biasing force of the spring.